Editing How to Rebuild a Brembo Caliper (section)

=== Reassembly ===


[[Image:Brembo_Caliper_20.JPG]]


Install a new parking brake drive plate shaft O-ring, if needed.
Reinstall the flat washer, needle bearing, and ball bearing drive plate of the parking brake in the caliper body. Make note of where the three ball bearings are; you will need to mate them with the driven plate later.


[[Image:Brembo_Caliper_21.JPG]]

The internal assembly will go back together in this order:-

Wave washer

Flat washer

Ball bearing

Cone screw

Use some thread lock on the O-ringed screw on reassembly.
Install a new O-ring on the screw.


[[Image:Brembo_Caliper_22.JPG]]


To reassemble the caliper, insert assembly into the piston and snap the {coat-hanger quality) internal snap ring into the piston.


[[Image:Brembo_Caliper_23.JPG]]


The snap ring groove is just inside the piston.


[[Image:Brembo_Caliper_24.JPG]]


Take the internal snap ring with the tabs, point the tabs downward, and use the tabs to clip the snap ring into the bottom
edge of the piston.


[[Image:Brembo_Caliper_25.JPG]]


Then screw the worm shaft into the piston as far as it will go.
Install the new piston seal.


[[Image:Brembo_Caliper_26.JPG]]


Stretch the new dust boot over the bottom of the assembled piston, leaving the lower edge of the boot to hang down. You will have to hold the piston over the bore and insert the boot lip into the groove all the way around before inserting the piston into the bore. The boot should look even (no bumps) if done properly.
Make note of where the ball bearing detents are.


[[Image:Brembo_Caliper_27.JPG]]


This is the tricky part. With the boot in the groove, centre the piston to begin pushing it into the bore. Use a c-clamp with a socket covering the parking brake shaft sticking out the bottom, making sure the clamp is pushing the piston straight down. Besides the normal problem of getting past the boot lip and the seal, the driven plate detents and the drive plate ball bearings must mate, otherwise you will not be able to push the piston down far enough for the internal snap ring to find it’s groove.
If the clamp seems to come to a stop and you have not heard the snap ring snap into place, try to rotate the clamp to rotate the piston and line up the ball bearing detents.
A second way is to temporarily attach the parking brake lever under the clamp to rotate the lever, which will move the drive ball bearings back and forth to line everything up.
Rotate the lever clockwise when facing the lever, as this also screws the threaded shaft into the cone shaped washer (ensuring that the piston is not bottoming on the parking brake adjustment.)
In any case, the piston will seem to be very low, lower than the dust boot wrinkles, before the snap ring engages. If the snap ring does not engage, the parking brake system has nothing to push on to “disengage.”

Hint 1: A G-clamp may not provide sufficient force to engage the snap ring.  It may take 2-3 tons of pressure on a bench press before you hear the snap ring click into position.

Hint 2: Sometimes you can't push on the brake lever arm with the C-clamp to insert piston, you need to take off the arm and push on casting using socket.

Hint 3: Tons of force may not really be necessary.  There are two ways to do it even without a G-clamp. The first way is to wind in the worm shaft in to compress the spring - if you're lucky there will be enough friction to hold the spring compressed.  Listen whilst you reassemble it in case it comes un-sprung.  If it stays sprung, you should be able to get the snap ring to snap by hand pressure on the piston. Alternatively, mount the caliper in a vice. Using a pair of circlip pliers or whatever tool you use to retract the piston, wind the piston clockwise while at the same time applying a reasonable amount of pressure to drive the piston into the caliper.  You should hear the circlip click in place.

When the snap ring engages, reinstall the hex head stop peg.
Using the parking brake lever, rotate the parking brake shaft while looking down into the stop peg boss. You will see the detent in the foot of the worm shaft. Screw in the stop peg so it engages the detent.
You can check the proper operation by now rotating the parking brake lever again (which will push the piston out) and then rotating the opposite direction (which should slightly pull the piston back in.) With larger swings of the lever, this becomes a ratcheting action, so repeated back and forth with the lever will eventually move the piston further and further out; if the snap ring is engaged properly, the piston will slightly retract after each lever movement.


[[Image:Brembo_Caliper_28.JPG]]
[[Image:Brembo_Caliper_29.JPG]]


Once installed, the new 38mm calipers look exactly like the standard system.


Notes:
The brakes usually have to bled twice. It seems that air is trapped in the piston (the recess for the threaded parking brake adjustment rod) that isn’t flushed out during caliper installation.
The O-ring screw is a 10-32 thread. About 10% of the time it breaks when trying to remove it.

[[Category:Brakes]]
[[Category:Lotus Elise]]
[[Category:S1]]
[[Category:S2]]